U.S. patent number 7,914,531 [Application Number 11/244,407] was granted by the patent office on 2011-03-29 for bone fixation system and methods.
Invention is credited to David S. Geller, Dan Zlotolow.
United States Patent |
7,914,531 |
Geller , et al. |
March 29, 2011 |
Bone fixation system and methods
Abstract
An internal system and method for fixating an appendicular bone
fracture in an individual. A plurality of fixating screws, each of
which is adapted for placement in the bone at an anatomically
favorable position, and at least one of which is adapted to provide
interfragmentary reduction of the bone fracture are connectable to
a rigid rod to provide bone fixation. A fracture positioning clamp
for holding a reduced fracture in place until application of a
fixation system.
Inventors: |
Geller; David S. (New York,
NY), Zlotolow; Dan (Baltimore, MD) |
Family
ID: |
43769827 |
Appl.
No.: |
11/244,407 |
Filed: |
October 6, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60615965 |
Oct 6, 2004 |
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60695857 |
Jul 5, 2005 |
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Current U.S.
Class: |
606/60;
606/278 |
Current CPC
Class: |
A61B
17/8605 (20130101); A61B 17/68 (20130101); A61B
17/88 (20130101); A61B 17/8645 (20130101); A61B
17/7041 (20130101); A61B 17/8038 (20130101) |
Current International
Class: |
A61B
17/58 (20060101) |
Field of
Search: |
;606/54,55,57-60,264,266,267,270 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Barrett; Thomas C
Assistant Examiner: Woodall; Nicholas
Attorney, Agent or Firm: Rothwell, Figg, Ernst & Manbeck
pc
Parent Case Text
This application claims benefit of U.S. Provisional Patent
Application No. 60/615,965, filed Oct. 6, 2004 and U.S. Provisional
Patent Application No. 60/695,857, filed Jul. 5, 2005, both of
which are hereby incorporated in their entireties into the present
application.
Claims
What is claimed is:
1. A method for internal fixation of an appendicular bone fracture
in an individual, said method comprising: providing a plurality of
fixating screws; placing each of said fixating screws in the bone
in an anatomically favorable position, wherein at least one of said
fixating screws provides interfragmentary reduction of the bone
fracture in lag fashion, and wherein at least one of said fixating
screws comprises an open end which comprises inner threads;
providing a plurality of clamps, each adapted for placement over
the end of at least one of the fixating screws and adapted to be
coupled to a rigid rod; placing the clamps over the ends of
fixating screws; providing a plurality of locking screws adapted to
be fitted within the open end of at least one of the fixating
screws, for securing the clamps to the fixating screws; providing
at least one rigid rod, adapted to be coupled with the clamp;
providing a plurality of fasteners for securing the clamps to the
at least one rigid rod; fastening the rigid rod to a plurality of
clamps to provide fixation.
Description
FIELD OF THE INVENTION
The present invention relates generally to medical devices, and
more particularly to bone fracture fixation systems.
BACKGROUND OF THE INVENTION
All United States Patents referred to herein are hereby
incorporated by reference in their entireties. In the case of
conflict, the present specification, including definitions, will
control.
Numerous methods and devices are known and available for
stabilizing and fixating bone fractures in various bone types in an
individual. These include both external and internal fixation
systems. For example, U.S. Pat. No. 6,682,561 refers to an
implantable spinal, vertebral replacement device that includes a
tubular cage and a series of plates and screws. Other spinal
stabilization systems used in posterior spinal fusions also involve
plate and screw constructs. Such systems are limited in their
effectiveness in that screw placement depends on the locations of
the plate holes. As a result, screws are placed in sub-optimal
locations and at sub-optimal angles that could threaten
neurovascular injury and compromise fracture fixation. Recent
spinal stabilization techniques have employed modular rod and screw
systems that allow more flexibility in screw placement, by
permitting the screws to be placed first, after which they are
affixed to a common rod.
Various other systems exist for fixating bones. U.S. Pat. No.
6,660,009 refers to nails and a nail insertion device used in the
fixation of distal radial fractures. U.S. Pat. No. 6,692,496 refers
to an internal fixation device that employs the axial insertion and
anchoring of elongate members into long bones to treat
fractures.
U.S. Pat. No. 6,585,736 refers to external fixation of a fractured
radius using a variety of components, including rods, pins, clamps,
and sliding plates. U.S. Pat. No. 6,716,212 refers to an external
rod and clamp construct for use in immobilizing or stabilizing
unexposed long bone fractures in patients who are unable to undergo
definitive fixation. The system involves percutaneous pins placed
through stab incisions, which pins are then fastened to external
rods.
The fixation of certain fractures, such as comminuted
intra-articular fractures in the appendicular skeleton, is not
adequately addressed in the art. Important considerations in
fixating such fractures include the need for proper anatomic
alignment and rigid fixation. Current fixation techniques typically
rely upon the use of plates and screws once an anatomic reduction
has been achieved. These plate systems do not allow for flexibility
in screw placement, which is necessary for achieving optimal
interfragmentary fixation. Often, screws are used outside of the
plate construct in order to augment fixation.
FIG. 1 illustrates a typical internal fixation device used in the
art, which exhibits the above inadequacies. In this figure, the
device is employed in an effort to fixate fractures 20 in a bone
10. The fractures have resulted in several fragments 30 being
present. This device involves one or more plates 40 which have
within them a series of holes 50 for securing the plates to the
bone using screws 60. As can be seen from the figure, the placement
of the screws is entirely dictated by the locations of the holes in
the plates. These limitations in screw placement, including the
angle in which the screw can be inserted, frequently result in
anatomically inadequate or inappropriate placement of screws, which
can lead to improper fixation, limited effectiveness in healing,
limited range of motion, and damage or disruption to nerves or
vessels.
Recent advances in plate fixation systems have incorporated locking
screw designs in which the screw head threads into the plate,
providing a fixed-angle screw-plate construct. This concept,
adapted from anterior spinal instrumentation systems, has increased
the rigidity of the overall construct and the pull-put strength of
the screws, but at the cost of further limiting angular screw
positioning.
There is thus a need in the art for a system and method that
mitigates or eliminates the above disadvantages and inadequacies
seen in the art, while maximizing the advantages of rigidity via
fixed angle devices. In particular, there is a need for a system
and method for providing a strong, rigid bone fixation in a manner
that is anatomically appropriate for the individual.
SUMMARY OF INVENTION
To overcome the problems associated with previous bone fixation
systems, the present invention provides systems and methods for the
stabilization or fixation of bone or bony fragments in the
appendicular skeleton of an individual. In an aspect, the invention
provides a modular rod and screw system comprising a series of
screws placed in optimal anatomic position, to which a rod or rods
are attached using multiple connectors and fasteners. This system
allows the clinician a greater degree of flexibility and choice of
screw position than is afforded by conventional systems,
particularly plate systems as described above.
In a preferred embodiment, the invention provides an internal
system for fixating an appendicular bone fracture in an individual.
The system comprises a plurality of fixating screws, each adapted
for placement in the bone at an anatomically favorable position,
wherein at least one of the fixating screws is adapted to provide
interfragmentary reduction of the bone fracture and at least one
rigid rod attachable to the fixating screws to provide fixation of
the bone fracture.
In an aspect, the invention also provides a system for fixating an
appendicular bone fracture in an individual, the system comprising
a plurality of fixating screws, each adapted for placement in the
bone at an anatomically favorable position, and at least one rigid
rod attachable to the plurality of screws by a plurality of
connecting devices.
The invention also provides a fracture positioning clamp that
serves to temporarily hold a fracture in place after reduction so
that screws, such as lag screws, can be appropriately placed in an
anatomically favorable position to secure the reduced fracture in
place until a rigid fixation system is applied. The screws may
serve as the fixating screws of a fixation system described herein,
or of any other appropriate fixation system that would benefit from
the unique advantages provided by the fracture positioning clamp.
Alternatively, additional fixating screws may be applied as
appropriate, as described herein in connection with fixation
systems.
In an embodiment, the fracture positioning clamp comprises a
plurality (preferably two) of holding devices, each of which
comprises a substantially cylindrical housing within which is
located a mechanism for imparting a direct or indirect depressional
and/or rotational force upon a partially threaded rod. The
depressional and/or rotational force causes each holding device to
securely engage the partially threaded rod, thereby locking the
holding devices in position relative to each other and thereby
holding the reduced fracture in place until the fracture is further
secured (such as with a lag screw) and a fixation system
applied.
The invention further provides methods of reducing and fixating
bone fractures using the systems and clamps described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a photograph of a conventional prior art plate and screw
system for fixating bone fractures.
FIG. 2 is a photograph of a bone fixation system in accordance with
the invention.
FIG. 3 is a photograph of a bone fixation system in accordance with
the invention.
FIG. 4 is a schematic showing a bone into which fixating screws
have been placed in accordance with the invention.
FIG. 5 depicts an exemplary fixating screw in accordance with the
invention.
FIG. 6 illustrates placement of a clamp in relation to a fixating
screw in accordance with an embodiment of the invention.
FIGS. 7-7C show exemplary clamps in accordance with embodiments of
the invention.
FIGS. 8 and 8A illustrate a relationship between a clamp, fixating
screw, and rod in accordance with an embodiment of the
invention.
FIG. 9 illustrates placement of a tightening screw in relation to a
fixating screw in accordance with an embodiment of the
invention.
FIGS. 10-10B are schematics depicting fixation systems in
accordance with the invention.
FIG. 11 depicts a fracture positioning clamp in accordance with the
invention.
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description, reference is made to various
specific embodiments in which the invention may be practiced. These
embodiments are described with sufficient detail to enable those
skilled in the art to practice the invention, and it is to be
understood that other embodiments may be employed, and that
structural and logical changes may be made without departing from
the spirit or scope of the present invention.
As used herein, an internal fixation system relates to a system
that allows for soft tissue closure.
As used herein, an "anatomically favorable position" refers to any
position chosen for screw placement that is deemed medically or
anatomically beneficial to achieve proper fixation while minimizing
potential for damage to bone, nerves, vessels, or other tissue.
As used herein, "interfragmentary reduction" and "interfragmentary
compression" refer to the bringing together of two or more bone
fragments either positionally or in lag fashion.
An "intra-articular" fracture is a fracture occurring at an
articulated interface between bones.
As used herein, a "rod" refers to any rod or rod-plate combination
construct which can be used to link or reversibly attach the
various screws and connectors in accordance with the invention. The
rod can be sized and shaped as appropriate to achieve the results
described herein. Similarly, a "partially threaded rod" refers to a
rod described as above, which contains threads on at least a
portion of its surface to engage other components of the fracture
positioning clamp as described herein.
The present invention provides an internal system for fixating an
appendicular bone fracture in an individual. The system comprises a
plurality of fixating screws, each adapted for placement in the
bone at an anatomically favorable position, wherein at least one of
the fixating screws is adapted to provide interfragmentary
reduction of the bone fracture, and at least one rigid rod
attachable to the fixating screws to provide fixation of the bone
fracture. The invention further provides methods of fixating bones
using such systems.
The present invention overcomes the limitations of screw placement
dictated by plate fixation and allows for optimal interfragmentary
screw fixation, which ultimately is locked into the overall
construct. This can be accomplished in accordance with methods of
the present invention by placing all fixating screws in the desired
locations as appropriate according to the individual fracture
pattern.
In a preferred embodiment, once interfragmentary screw fixation is
accomplished, low-profile clamps can be placed over each screw
head. Locking screws can then be provisionally placed into the
screw head, loosely holding the clamps in place. A rigid rod, which
may be contoured or otherwise appropriately shaped, is fitted into
the clamps and locked in place using fastener screws. The screws
are finally locked into the clamps by tightening the locking
screws. The tightening screws thread into the screw head and force
it to expand, locking the entire construct.
Referring now to the drawings, where like elements are designated
by like reference numerals, FIGS. 2-10B illustrate preferred
systems and methods in accordance with the present invention, which
can be employed to prevent the problems associated with devices
currently used in the art, such as that illustrated in FIG. 1.
FIG. 2 illustrates a preferred embodiment of the present invention
as it is used to achieve internal fixation of a bone fracture or
fractures in the appendicular skeleton of an individual. FIG. 3
shows an alternate view of the embodiment depicted in FIG. 2.
As shown in FIG. 2, a system in accordance with the present
invention is used to achieve fixation of a bone 10 having fractures
20 resulting in one or more fragments 30. The system of the present
invention is applicable for use in fixating a bone or bone
fragments in any mammalian individual, preferably a human. In a
preferred embodiment, the system is adapted for use in the fixation
of an intra-articular fracture, such as would occur, for example,
in the distal humerus.
In the illustrated embodiment, the system comprises fixating screws
70 placed in the affected bone 10 in anatomically favorable
positions. These fixating screws are preferably made from metal,
but can comprise any material suitable for fabricating a screw
adapted to be securely placed within a bone in an individual.
Moreover, the fixating screws can be sized as appropriate. For
example, the screws can be sized so that a minimal amount of the
screw protrudes from the bone (as illustrated, for example, in
FIGS. 4 and 10). The fixating screws can be placed as desired, in
any position deemed appropriate for achieving maximum benefit to
the individual, with at least one fixating screw 90 being placed to
provide interfragmentary reduction of the bone fracture. In the
present invention, the placement of the fixating screws 70,90 is
not dictated or determined in any way by other components of the
system. Rather, in contrast to known internal and external bone
fixation devices, the fixating screws of the present invention can
be placed in locations determined by one of skill in the art to be
most beneficial for achieving the desired result, including, for
example, the avoidance or minimization of nerve or vessel damage or
excessive soft tissue stripping or injury, while achieving a
strong, rigid fixation, and in many cases achieving the
preservation or enhanced recovery of ranges of motion not possible
with other fixation devices.
Following placement of the fixating screws 70,90, one or more rigid
rods 80 is connected or attached to the fixating screws by any
appropriate connecting mechanism 85. More than one rod can be used,
and it is not necessary for each individual rod to simultaneously
connect to each individual screw. As in the figure, each of a
plurality of rods can be connected to as many screws as one of
skill in the art deems appropriate to achieve a rigid fixation of
the bone fracture. Once connected securely, the system holds the
bone fragments in place, providing a rigid fixation, allowing the
bone to repair itself and heal appropriately. Rod 80 can be
fabricated from any appropriate material, but preferably comprises
a metal, such as, without limitation, medical grade titanium,
stainless steel, or an alloy thereof. The rod can be bent or
otherwise shaped as necessary, as shown in FIGS. 2 and 3, to be
adapted for connection to the fixating screws.
The rod need not be uniform in shape throughout its length, and may
include a combination of rod-like portions and plate like portions.
In an embodiment, the rod may, for example, have a rod-like portion
that merges into a plate-like portion, wherein the rod-like portion
is used where prior placement of screws is desired or critical, and
the plate-like portion is used to receive screws after the rod-like
portion is appropriately placed as described herein. Such a
construct can be useful, for example, in a fracture involving only
a distal aspect of the bone, so that proximal fixation is not
dependent on the same precision in screw location or angulation as
is distal fixation. Such an embodiment may offer potential
advantages in cost, ease of use, and adaptability to individual
fracture personality.
Referring now to FIG. 4, in a preferred method of the present
invention, a plurality of fixating screws 70 is provided, each of
which is placed in a bone 10 in an anatomically favorable position.
The skilled artisan, such as an appropriate medical professional,
has the flexibility of determining such positioning based on the
individual's anatomy or other needs deemed appropriate for
addressing the injury, rather than on any limitations dictated by
the instrumentation at his disposal. In preferred embodiments, one
or more of the screws 90 is placed in the bone to provide
interfragmentary compression of a fracture or fractures 20. The
method and system of the invention are particularly suited but not
limited to addressing intra-articular comminuted fractures of the
appendicular skeleton, which result in multiple bone fragments 30.
The skilled artisan can place as many or as few fixating screws 90
as he deems appropriate to achieve optimal interfragmentary
reduction of the various fragments. Moreover, he has the
flexibility to place the screws in locations and at angles that are
not achievable with conventional fixation devices. Once the
fixating screws have been placed securely in the bone, one or more
rods is connected to the fixating screws as indicated above to
achieve a rigid fixation. Therefore, in methods of the present
invention, bone fracture fixation is achieved using a system that
provides the flexibility to determine the most favorable locations
and positions of fixating screws, then securing these screws in
place with one or more rigid rods.
FIG. 5 illustrates a preferred fixating screw 100 for use in
accordance with the present invention. In the illustrated
embodiment, the screw comprises outer threads 110 for helping to
secure it within a bone, and for helping to bring and hold bone
fragments in tight cooperation when the screw is used for
interfragmentary reduction of two or more fragments. The
illustrated preferred fixating screw 100 also comprises an open end
125 having inner threads 120. The open end can have one or more
slots or gaps 128 to allow for slight expansion of the opening's
diameter upon insertion of a locking screw or other suitable
locking mechanism. In a preferred embodiment, the connector for
connecting the rod or rods to the fixating screws is a clamp, which
can be coupled to the fixating screw and adapted to receive and
secure the rod.
FIG. 6 illustrates an embodiment in which the clamp 130 is adapted
to be placed over the open end 125 of the fixating screw 100. In
this embodiment, the clamp comprises a swivel/toggle mechanism 140
which allows for an initially loose fit, later to be secured
tightly once the rod is in place. This mechanism permits
flexibility in the relative positions of the various components
prior to final tightening.
FIG. 7 illustrates a particularly preferred embodiment of a clamp
150 for use in accordance with the invention. As shown, the clamp
150 has an opening 160 for placement over the end of a fixating
screw. The illustrated embodiment includes a mechanism 165, such as
the swivel/toggle mechanism described above. In the illustrated
embodiment, the clamp comprises members 170, 180 that define an
opening 190 through which a rod may be placed in accordance with
the invention. Any suitable means can be used to secure the rod and
clamp together. In the illustrated embodiment, the clamp 150 is
adapted to receive a fastener screw 200 to secure the rod to the
clamp.
FIG. 7A shows an alternate embodiment of a clamp 150 in accordance
with the invention. In this embodiment, a rod 80 is placed in
cooperation with the clamp 150.
FIG. 7B illustrates an alternate view of a clamp in accordance with
the invention. In this illustrated embodiment, a locking screw 240
as described herein is also shown.
FIG. 7C illustrates another embodiment of a clamp 150 in accordance
with the invention. This illustrated embodiment includes a
swivel/toggle mechanism 140 as described herein.
FIGS. 8 and 8A illustrate the cooperation between certain
components of a system in accordance with the invention. A fixating
screw 70, 100 comprising an open end 125 having slots or gaps 128
to allow for expansion, is shown in side view. A clamp 150 is also
shown in side view, and is shown placed over the end of fixating
screw 70, 100. As shown here, the clamp comprises a mechanism 220,
such as a swivel/toggle mechanism, which allows for flexibility in
achieving an initially variable positional relationship between the
clamp 150 and fixating screw 70. For example, when fixating screw
70 is securely placed in a bone, the clamp 150 can be initially
placed loosely over the end of the fixating screw. The mechanism
220 then allows for the clamp to be swivelled 235 or toggled 230 as
necessary prior to final tightening or locking of the complete
fixation system. A rod 80 is shown in cross-sectional view and is
placed within opening 190 of the clamp. In the illustrated
embodiment, the clamp 150 has an additional opening or hole 210
adapted to receive a fastener screw 200 to secure a rod 80 to one
or more clamps. A variety of other styles and versions of clamps,
fasteners, connectors, mechanisms, and securing devices can be used
in accordance with the present invention to achieve the results
described herein.
In the embodiment illustrated in FIG. 9, a locking screw 240 having
outer threads 250 is placed within the opening 125 of the fixating
screw 70 following placement of the fixating screw in a bone,
placement of a clamp 150 or other suitable connector over the end
of the fixating screw, and placement of a rod in secure cooperation
(not shown) with the connector. In a preferred method, the outer
threads 250 of the locking screw 240 engage the inner threads 120
of the fixating screw 70. Upon tightening, the slots 128 allow the
opening 125 to expand, thereby securing the clamp or other
connector to the fixating screw, preferably at a fixed angle. This
process can be repeated with other fixating screw/connector
combinations, thereby rigidly securing the entire system together
to achieve a rigid fixation of the bone when the various components
of the system are engaged.
FIGS. 10-10B are schematics showing preferred embodiments of the
internal fixation system as it may be used in the fixation of a
comminuted bone fracture. As illustrated, fixating screws 70 (and
90) are placed in a bone 10 in various desired locations and
positions. The illustrated bone exhibits several fractures 20,
resulting in multiple bone fragments 30. Some of the fixating
screws 90 are placed in positions to achieve interfragmentary
reduction of the fractures. A plurality of connectors 85 have been
secured to the fixating screws, 70, 90. Two separate rods 80 are
attached to the connectors to provide and maintain a strong rigid
fix of the bone. One or more cross-clamps or other suitable
connectors may also be employed to link together two or more rods,
thereby providing increased overall system strength.
The invention further provides a fracture positioning clamp, as
illustrated, for example, in FIG. 11. The fracture positioning
clamp is useful while preparing the fracture for the ultimate
placement of a fixation system, such as an internal system
described herein. In the illustrated embodiment of the fracture
positioning clamp, two "pen-type" holding devices are shown. Each
such device includes a housing (1) within which is a series of
components that cooperate to lock a partially threaded rod (2) in
place upon application of a depressive force. The fracture
positioning clamp thus serves to temporarily hold a fracture in
place after reduction so that screws, such as lag screws, can be
appropriately placed in an anatomically favorable position to
secure the reduced fracture until a rigid fixation system can be
applied. The screws may serve as the fixating screws of a fixation
system described herein, or of any other appropriate fixation
system that would benefit from the unique advantages provided by
the fracture positioning clamp. Alternatively, additional fixating
screws may be applied as appropriate, as described herein in
connection with fixation systems.
In using the fracture positioning clamp of the illustrated
embodiment, for example, a button mechanism (A) located on either
holding device is depressed once the fracture is properly reduced
or positioned. This action will lock the holding devices in
position relative to each other, subject to fine adjustments, if
necessary, as noted below. Prior to this locking, the holding
devices each enjoy six degrees of freedom, thus allowing for a
great range of motion that enables one to manipulate the fracture
to insure that it is optimally reduced and placed in a position
that is satisfactory to one of skill in the art prior to rigid
fixation.
Upon the depression described above, the button mechanism contacts
a component within the housing, such as the illustrated crown (B),
that is adapted to engage the depressed button at one end and to
contact a plunger (D) at the other end. Thus, upon engagement of
the component (illustrated here as the crown) with the depressed
button, the plunger is forced to depress and, preferably, rotate.
The plunger's default position is raised or open, and can be held
in such position via any suitable mechanism, such as the spring (C)
shown in FIG. 11.
Any suitably-shaped or configured combination of button mechanism
and component with which it engages can be used provided it
achieves the desired function as described above. In alternate
embodiments, for example, rather than a pen-type button and
crown-shaped component configuration, a ratchet mechanism can be
used to exert and maintain the depressive (and rotational) force
and resulting movement and functions.
Upon depression of the button or advancement of the ratchet, the
plunger engages a component that is preferably substantially
spherical in shape (E). This component becomes locked between the
plunger and a pad (F). The plunger is thus composed of a material
that permits it to impart large frictional forces and resist motion
when engaged with the substantially spherical component. This
material can be any suitable material that effectively achieves or
allows the result described above, but preferably includes a
rubberized material or a highly beaded/roughened surface.
Similarly, the substantially spherical component preferably
includes a rubberized material or a metal with a highly beaded or
roughened surface. The pad is preferably comprised of the same or a
similar material as the plunger, i.e. a material having high
frictional force characteristics. Until the substantially spherical
component is engaged and locked into position, it can move freely
within the housing.
In the illustrated embodiment, a sheath (H) is attached or coupled
to the substantially spherical component, the sheath being adapted
to accept the partially threaded rod. A distractor (J) is
attachable to the sheath, and is adapted to accept the partially
threaded rod and engage it at the portion of the rod bearing
threads. The distractor therefore allows for small changes in
length in either direction along the rod once the apparatus is
locked in place. This can be accomplished, for example, by rotating
the distractor in the desired direction, allowing the threads on
the rod to be used in cooperation with the distractor to force the
holding devices to move relatively closer or further away from each
other. This configuration thus allows one to make fine adjustments
even after the system is secure, when such small changes (e.g. up
to a few mm) are desired to optimize the fracture reduction.
The distractor may be adapted to accept a device such as a tommy
bar (I) or other suitable mechanism which is capable of increasing
the moment arm and more easily imparting a rotational force.
In an embodiment, a compressor stop (K) is included within the
substantially spherical component of one of the holding devices.
This compressor stop is preferably a miniature plunger that serves
to engage the partially threaded rod. Once the plunger mechanism is
depressed, the substantially spherical component and the partially
threaded rod are simultaneously engaged. The default position of
the miniature plunger is in the open or raised position, which is
achieved by any suitable mechanism, preferably a spring.
A female tube (G) is located at an end of each holding device. The
tube is adapted to attach the device to a screw placed in the bone.
This tube fits tightly over the screw allowing the holding device
to impart forces through the screw and ultimately to the bone. In
this manner, reduction forces can be applied by the hands of the
one operating the system, through the holding devices, through the
screws and to the bone. To insure that the screws yield sufficient
protruding length to allow the holding device to attach, a
screwdriver with a shaft that can detach from the screwdriver's
handle once the screw is in place, can be utilized. In such an
embodiment, the shaft remains as an extension of the fixated screw,
so that the holding device can be fitted tightly over it via the
female tube (G).
The locking of the components of the fracture positioning clamp in
place, thus securing the fracture in the desired position,
facilitates the placement of further screws, if desired, such as
the fixating screws employed in connection with the internal
systems described herein, so that the internal system can be
utilized as described.
Thus, for example, one can utilize the fracture positioning clamp
in concert with an internal fixating system as follows. When a
fracture (such as in a long bone, ankle bone, or other appendicular
skeletal location) has occurred for which rigid fixation is
desired, screws as described above in connection with the fracture
positioning clamp can be placed on either side of the fracture
site. The fracture positioning clamp can then be placed on the
screws as described above. Before locking the clamp, due to its
allowance of a great range of motion, the fracture can be
manipulated until optimal reduction and positioning is achieved.
The fracture positioning clamp can then be locked, and finely
adjusted if desired, as noted above. Once satisfactory fracture
reduction and positioning is achieved, and the fracture positioning
clamp is securely locked, one or more screws, such as lag screws,
can be placed across the fracture site to stabilize the reduction.
The fracture positioning clamp can then be removed and an internal
fixating system as described herein can be applied. It is not
necessary that the fracture positioning clamp be removed prior to
applying the fixation system. Thus, fixating screws, such as those
described in connection with the internal systems of the present
invention, and/or the system itself, can be applied while the clamp
is still in place. The clamp can then be removed following rigid
fixation. Therefore, depending on whether the clamp is removed
prior to application of the fixation system or not, the screws on
which the holding devices had been secured, the lag screws, or any
additional fixating screws can be used to secure the rod and
connecting devices of the internal fixating systems described
herein.
Moreover, while the fracture positioning clamp is suitable for use
in concert with the internal fixation systems described herein,
other suitable fixation systems and apparatus may be used following
the reduction and positioning of the fracture achieved through the
use of the fracture positioning clamp. Thus, the fracture
positioning clamp provides a device and method for achieving an
accurate and precise reduction and positioning of a bone prior to
rigid fixation, that is not readily achieved through known fixation
methods.
In an aspect, the invention thus provides a system and method for
fixating an appendicular bone fracture in an individual, the system
comprising a plurality of fixating screws, each adapted for
placement in the bone at an anatomically favorable position, and at
least one rigid rod attachable to the plurality of screws by a
plurality of connecting devices.
The invention also provides a fracture positioning clamp comprising
a plurality of holding devices each holding device comprising a
substantially cylindrical housing within which is located a
mechanism for imparting a direct or indirect depressional force
upon a partially threaded rod. The depressional force causes each
holding device to securely engage the rod, thereby locking the
holding devices in position relative to each other and thereby
holding the reduced fracture in place until the fracture is further
secured (such as with a lag screw) and a fixation system
applied.
Numerous additional applications are also within the scope of the
present invention, as one of ordinary skill in the art will readily
recognize. In a further embodiment, for example, the system and
method can be applied to a severely comminuted fracture of the
distal fibula (i.e., an ankle fracture) in a manner similar to
bridge plating. In such an embodiment, the fragments and fracture
bed are not disturbed, with the system being fixated both proximal
and distal to the fracture location. Avoiding disruption of the
fracture itself, while still maintaining length and position,
avoids soft tissue stripping and loss of osteoinductive factors,
such as bone morphogenetic proteins (BMP) found endogenously in
fracture hematoma. The fixation system of the present invention
also can be placed in a percutaneous or limited open manner, which
is possible due in part to the ability to use very small screws,
clamps and other connectors, with rods that are likewise themselves
very narrow.
In still further embodiments, the invention is useful in, for
example, forearm fractures in which rigid fixation of the radius
and ulna is required. These two long bones act and articulate with
one another in a manner similar to that of a joint. Typically in
the art, rigid fixation of such fractures is achieved via a limited
contact dynamic compression plate (LC-DCP), which allows the
fracture ends to be forced together, thereby resulting in
interfragmentary compression, which in turn confers significantly
increased rigidity. The amount of compression in typical systems,
however, is limited by the fact that the screw head itself drives
the compressive force. Because a typical screw head is merely
millimeters in size, it can only force the plate, and in turn, the
bone, to compress a few millimeters at a time. It may be possible
with present systems to then loosen one end and compress a few more
millimeters with the next screw that is placed, but such a system
is not optimal. The present invention overcomes this disadvantage,
by allowing for an unlimited amount of compression in a single
motion or step. Moreover, as described, the fixating screws can be
placed in optimal anatomic position and orientation. Additionally,
the time typically involved in contouring a very rigid plate to the
shape of the bone can be eliminated by the use of the present
system, due at least in part to the ability to use a rod with
narrow width. The present system has specific usefulness in
non-union, where compression and bone grafting are keys to
healing.
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